The present invention relates broadly to a reciprocator sleeve for use in an offset printing press machine having an envelope feeder which enables the feeder to convey windowed envelopes from an envelope stack into a pair of pinch rollers without scratching or otherwise marking the windows of the envelopes.
The ubiquitous "windowed" envelope is familiar to all as the harbinger of both bills and checks alike. Windowed envelopes, such as the standard No. 10 billing envelope, are constructed, as are conventional envelopes, from a folded sheet of paperstock, but differ in having a window generally configured as a 4.5 inch (11.43 cm) by 1.125 inch (2.86 cm) rectangular opening located adjacent the lower left corner of the front face of the envelope. The window is provided so that an address printed on a corresponding portion of the bill, check, or the like contained in the envelope may be revealed without having to show the remainder of the correspondence. Accordingly, an underlayment of clear, or at least translucent, plastic film is adhered to the inside of the envelope both to seal the window and to allow for the viewing of the selected portion of the correspondence contained in the envelope. Typically, such films are formed of a clear, matte, or rubber-modified polystyrene material having a film thickness of from about 0.00115 inch (0.02921 ram) to about 0.002 inch (0.0508 ram).
The use of a windowed envelope to reveal an address printed on its contents advantageously obviates the need for the sender to reprint the address of the intended recipient on the face of the envelope. Indeed, by preprinting a return address or logo on the face of a windowed envelope, a sender may most economically effect a mass mailing of correspondences such as bills, payments, advertising materials, or the like to customers or creditors. In this regard, offset printing or "letter press" machines equipped to automatically feed a stack of envelopes to an associated offset printing press head are commonly employed by those in the printing industry. Typical of these printing machines are the JET PRESS.TM. machines manufactured by Halm Industries Co., Inc., 180 Glen Head Road, Glen Head, N.Y. 11545, and marketed under the model numbers JP-TWOD-P, JP-TWOD-6D, JP-TWOD-P-D, JP-FWOD, and JP-FWOD-W. The operation of such machines is described in detail by Harrison, U.S. Pat. Nos. 3,892,400; Schilpf, 3,796,426; and Quinci et al., 4,375,190, the disclosures of which are expressly incorporated herein by reference.
Generally, the envelope printing machines common in the art employ an envelope feeder to automatically deliver envelopes to the printing press head. Such feeders generally involve an arrangement of front, lateral, and back guides for positioning an envelope stack above a reciprocator. The reciprocator is formed as having a cylindrical head for reciprocating rotation about its longitudinal axis to provide a feed and a return stroke which describe generally arcuate loci between the envelope stack and a pair of pinch rollers leading to a feed or conveyor belt disposed beneath the reciprocator for transport of the envelopes to the printing press head. From one end of the cylindrical reciprocator head, an elongate shaft is provided to extend to a drive assembly for reciprocatingly rotating the head about its longitudinal axis. The other end of the reciprocator head is joined in fluid communication with a vacuum source for applying a constant negative pressure differential to the front face of the bottommost envelope in the stack through a plurality of axially-aligned vacuum port openings formed into the head. The constant negative pressure differential applied to the front face of the bottommost envelope in the stack through the generally rectangular vacuum ports retains that envelope on the head for its conveyance along the generally arcuate locus of the feed stroke from the envelope stack and into the pinch rollers. The pinch rollers are rotationally driven to effect a drawing of the envelope from the reciprocator head in an angular direction generally opposite that of the return stroke of the head.
Heretofore, the use of such envelope printing press machines to preprint return addresses onto windowed envelopes has been plagued with one nagging problem, to wit, that of the printing process impressing scratches or other markings into the polymeric film underlayment of the window. Indeed, apart from detracting from the aesthetics of the envelope, the generally vertical scratches or other lines scored by the printing machine across the widthwise extent of the window have been known to interfere with the scanners employed by the U.S. Postal Service to read the bar codes which may be printed below the address. Such bar codes encrypt the address in a machine-readable series of vertical lines, and allow the envelope to be automatically dispatched to the proper location for delivery by a postal carrier. As the automatic sorting of mail represents a cost savings to the Postal Service, bar-coded envelopes may be mailed at a reduced postage rate mid, understandably, are especially attractive to business and the like which generate a significant amount of outgoing mail. The scratches or other lines cut into the envelope windows by the above-described printing press machines common in the industry, however, may cause the postal scanners to misread the bar code. The misreading may result in the envelope being delivered to the wrong address, or may unnecessarily delay delivery. Where billings are concerned, such delays are especially costly as representing a loss of revenue.
Not unexpectedly, it has been discovered that the scratches and other marks developed across the widthwise extent of the envelope windows by the previously described printing press are caused by the rotating action of the reciprocator head. Although the vacuum ports of the reciprocator head are oriented to contact the font face of the bottommost envelope in the envelope stack on a paperstock portion thereof, the ports are drawn across the widthwise extent of the window as the envelope is drawn from the head by the pinch rollers. Unfortunately, the constantly-applied vacuum and the drawing of the envelope from the head in an angular direction generally opposite that of the return stroke of the head only serve to accentuate the scoring of the window. Although felt pads and cloth tapes have been applied to the reciprocator head in attempts to alleviate the problem, these solutions have not met with success as interfering either with the development of a vacuum seal between the reciprocator head and the envelope, or in lacking the structural integrity to withstand the rigors of operation in a machine which may print up to about 40,000 envelopes per hour. The wearing or other structural failure of the tapes and pads heretofore known in the art has been seen as a maintenance problem as necessitating the stopping of production while replacement tapes or pads are installed. Understandably, such stoppages, often as frequent as daily or weekly, are not favored by the printing industry and often lead to a printer dispensing completely with such pads or tapes until a customer returns a printed envelope batch as unacceptable. Thus, it is apparent that another solution would be well-received by both the envelope printing industry and its customers.